1. Field of the Invention
The present invention relates to a vehicle control apparatus, a target lead-vehicle designating apparatus, and a vehicle control method, and particularly to a vehicle control apparatus, a target lead-vehicle designating apparatus, and a vehicle control method that specify a target lead-vehicle when a plurality of vehicles are traveling in line.
2. Description of the Related Art
Japanese Patent Application Publication No. 2005-115637 (JP-A-2005-115637) describes an apparatus that detects the running circumstances of vehicles around the host vehicle. The apparatus maps the positions indicated by information on vehicles ahead acquired from a radar device and information on vehicles ahead acquired from an inter-vehicle communication device in a mapping area based on the position of the host vehicle, and if overlapping vehicle positions are mapped, the reliability of information indicating the vehicle positions is calculated to estimate the vehicle positions on the basis of the calculated reliability.
The fuel efficiency and mutual safety of a group of vehicles traveling on a road exclusively for automobiles, such as an expressway, may be improved by having the group of vehicles travel in line and avoiding unnecessary acceleration and deceleration along with variations in inter-vehicle distance. When vehicles are traveling in line, it is necessary for a trailing vehicle to specify a leading vehicle and travel in accordance with the position and the speed of the leading vehicle. If the apparatus described in JP-A-2005-115637 is used to designate a target lead-vehicle when the host vehicle has engaged a vehicle-tracking mode, however, it may be difficult to determine which vehicle near the host vehicle should be identified as the target lead-vehicle, and the vehicle selected as the target lead-vehicle may be incorrect.